(1) Field of the Invention
The invention relates to a device for detecting light, in particular light emanating from a specimen in a microscope, preferably a laser-scanning microscope.
(2) Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Various types of detectors may be used for detection of light. These include, for example, CCD sensors, photomultipliers or photomultiplier tubes (PMT), and avalanche photodiodes (APD). Individual detectors are often combined to form one-dimensional or two-dimensional arrangements (line detectors or area detectors). Due to the design, the individual detector elements, also known as detector cells, are then spaced apart from each other. Therefore, such detector arrangements do not usually have a homogenous light-sensitive region. There are light-sensitive regions, which are interrupted by light-insensitive regions. When a bundle of light rays strikes such a detector arrangement, only that portion of the light striking the light-sensitive regions is detected. Light striking the light-insensitive regions cannot be detected. The efficiency of the detection arrangement is therefore reduced.
To solve the problem described above, it is known that those portions of light which would strike the light-insensitive regions of the detector arrangement without additional measures can be deflected onto the light-sensitive regions by means of light deflection elements. This increases the detection efficiency of the receiver, in the ideal case, up to the efficiency of a detector without light-insensitive regions.
The goal in general is the most homogeneous possible illumination of the light-sensitive regions, and reliably accurate focusing of the light on the light-sensitive regions. So-called lens arrays which focus the incident light by means of spherical elements and thus generate a light spot array are often used as light deflection elements. The detector is then arranged in such a way that the light-sensitive regions coincide with the light spot array. Such an arrangement is known from U.S. Pat. No. 6,157,017, for example. One disadvantage of the lens arrays described here is that they have spherical, i.e., curved surfaces. Such surfaces are much more complex to manufacture than planar surfaces.
DE 10038528 describes the use of lens arrays in the detection beam path of a laser-scanning microscope. Another approach is described in U.S. Pat. No. 5,952,645, where minor wedges are used as light deflection elements. One disadvantage of such an arrangement is the mechanical sensitivity of the narrower mirror wedges. In addition, this facilitates the deposition of dust between the wedges and thus on the light-sensitive regions.